1. Field of the Invention
This invention relates to a drive control system for an hydraulic elevator.
2. Description of Related Art
The present invention is an improvement over the invention of my prior U.S. Pat. No. 4,637,495 of January 1987 entitled Pressure/Viscosity Compensated Up Travel of an Hydraulic Elevator, incorporated herein by reference.
Hydraulic elevators should accelerate smoothly and approach their scheduled stopping positions gently and accurately and establish alignment of the bottom of an elevator car and a floor when the stopping point is approached from below at a creeping speed of travel during the final stage of approach. Different control systems have been developed for this purpose, which are however dependent in relatively large degrees on load and viscosity, and which suffer a delay in starting and an uncomfortable acceleration caused as result of said dependency.